Thread: compression ratio

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I am working on a sbc and I was needing to know what the easiest way to calculate compression ratio is

Originally posted by shawn74
I am working on a sbc and I was needing to know what the easiest way to calculate compression ratio is

http://streetmachinesoftablerock.com...opic.php?t=124

Great link Richard, thanks a bunch. I bookmarked the CR calculator. Got to start working up some numbers for my motor guy on that 514!!!!!

I like this calculator because of it's simplicity. I got it book marked for a quick reference. www.campbellenterprises.com/chevy_pistons.htm It's quick, and easy to make changes and also gives the cubic inches while calculating compression.

Make sure your figure DCR (dynamic compression ratio) as it is a better way to determine what ratio works with the camshaft you choose. 9.0:1 could be too much or not enough, depending on your cam specs. You want to shoot for something between 7.5-8.0:1 DCR to run on pump gas with iron heads.

Originally posted by DennyW
About 8.82:1 on 87 octane gas, so 9.1:1 should be ok on premium.

The rule of thumb for a "relatively stock" engine is about
9.5-10.0:1 on 93 octane (R+M/2 method).

The compression ratio you can get away with depends on a
great many factors...cam timing, intake/exhaust flow
quantity & quality, ignition timing, air/fuel ratio, operating
RPM, etc.

and squish